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Fair Value Measurements and Guarantees Recurring Measurements and Additional (Details) - USD ($)
$ in Millions
Jun. 30, 2026
Dec. 31, 2025
Energy Related Derivative    
Measured on a recurring basis    
Derivative Asset $ 266 $ 336
Derivative Liability (309) (340)
Carrying Amount [Member]    
Additional disclosures:    
Guarantees (34) (35)
Long-term debt, including current portion (30,318) (28,661)
Carrying Amount [Member] | Williams Companies Inc [Member]    
Additional disclosures:    
Long-term debt, including current portion (23,300) (21,649)
Carrying Amount [Member] | Transcontinental Gas Pipe Line Company, LLC [Member]    
Additional disclosures:    
Long-term debt, including current portion (5,890) (5,888)
Carrying Amount [Member] | Northwest Pipeline LLC [Member]    
Additional disclosures:    
Long-term debt, including current portion (749) (748)
Carrying Amount [Member] | MountainWest [Member]    
Additional disclosures:    
Long-term debt, including current portion (379) (376)
Fair Value [Member]    
Additional disclosures:    
Guarantees (26) (28)
Long-term debt, including current portion (29,835) (28,629)
Fair Value [Member] | Williams Companies Inc [Member]    
Additional disclosures:    
Long-term debt, including current portion (22,875) (21,556)
Fair Value [Member] | Transcontinental Gas Pipe Line Company, LLC [Member]    
Additional disclosures:    
Long-term debt, including current portion (5,827) (5,941)
Fair Value [Member] | Northwest Pipeline LLC [Member]    
Additional disclosures:    
Long-term debt, including current portion (747) (747)
Fair Value [Member] | MountainWest [Member]    
Additional disclosures:    
Long-term debt, including current portion (386) (385)
Level 1 [Member]    
Additional disclosures:    
Guarantees 0 0
Long-term debt, including current portion 0 0
Level 1 [Member] | Williams Companies Inc [Member]    
Additional disclosures:    
Long-term debt, including current portion 0 0
Level 1 [Member] | Transcontinental Gas Pipe Line Company, LLC [Member]    
Additional disclosures:    
Long-term debt, including current portion 0 0
Level 1 [Member] | Northwest Pipeline LLC [Member]    
Additional disclosures:    
Long-term debt, including current portion 0 0
Level 1 [Member] | MountainWest [Member]    
Additional disclosures:    
Long-term debt, including current portion 0 0
Level 2 [Member]    
Additional disclosures:    
Guarantees (10) (12)
Long-term debt, including current portion (29,835) (28,629)
Level 2 [Member] | Williams Companies Inc [Member]    
Additional disclosures:    
Long-term debt, including current portion (22,875) (21,556)
Level 2 [Member] | Transcontinental Gas Pipe Line Company, LLC [Member]    
Additional disclosures:    
Long-term debt, including current portion (5,827) (5,941)
Level 2 [Member] | Northwest Pipeline LLC [Member]    
Additional disclosures:    
Long-term debt, including current portion (747) (747)
Level 2 [Member] | MountainWest [Member]    
Additional disclosures:    
Long-term debt, including current portion (386) (385)
Level 3 [Member]    
Additional disclosures:    
Guarantees (16) (16)
Long-term debt, including current portion 0 0
Level 3 [Member] | Williams Companies Inc [Member]    
Additional disclosures:    
Long-term debt, including current portion 0 0
Level 3 [Member] | Transcontinental Gas Pipe Line Company, LLC [Member]    
Additional disclosures:    
Long-term debt, including current portion 0 0
Level 3 [Member] | Northwest Pipeline LLC [Member]    
Additional disclosures:    
Long-term debt, including current portion 0 0
Level 3 [Member] | MountainWest [Member]    
Additional disclosures:    
Long-term debt, including current portion 0 0
Fair Value, Recurring [Member] | Carrying Amount [Member]    
Measured on a recurring basis    
Equity Securities 123  
Fair Value, Recurring [Member] | Carrying Amount [Member] | Energy Related Derivative    
Measured on a recurring basis    
Derivative Asset [1] 266 336
Derivative Liability [1] (309) (340)
Fair Value, Recurring [Member] | Carrying Amount [Member] | Transcontinental Gas Pipe Line Company, LLC [Member]    
Measured on a recurring basis    
ARO Trust investments 321 356
Fair Value, Recurring [Member] | Fair Value [Member]    
Measured on a recurring basis    
Derivative Asset, Fair Value, Gross Asset 631 722
Derivative Liability, Fair Value, Gross Liability (919) (915)
Equity Securities 123  
Fair Value, Recurring [Member] | Fair Value [Member] | Transcontinental Gas Pipe Line Company, LLC [Member]    
Measured on a recurring basis    
ARO Trust investments 321 356
Fair Value, Recurring [Member] | Level 1 [Member]    
Measured on a recurring basis    
Derivative Asset, Fair Value, Gross Asset 392 431
Derivative Liability, Fair Value, Gross Liability (536) (497)
Equity Securities 123  
Fair Value, Recurring [Member] | Level 1 [Member] | Transcontinental Gas Pipe Line Company, LLC [Member]    
Measured on a recurring basis    
ARO Trust investments 321 356
Fair Value, Recurring [Member] | Level 2 [Member]    
Measured on a recurring basis    
Derivative Asset, Fair Value, Gross Asset 98 158
Derivative Liability, Fair Value, Gross Liability (213) (270)
Equity Securities 0  
Fair Value, Recurring [Member] | Level 2 [Member] | Transcontinental Gas Pipe Line Company, LLC [Member]    
Measured on a recurring basis    
ARO Trust investments 0 0
Fair Value, Recurring [Member] | Level 3 [Member]    
Measured on a recurring basis    
Derivative Asset, Fair Value, Gross Asset 141 133
Derivative Liability, Fair Value, Gross Liability (170) (148)
Equity Securities 0  
Fair Value, Recurring [Member] | Level 3 [Member] | Transcontinental Gas Pipe Line Company, LLC [Member]    
Measured on a recurring basis    
ARO Trust investments 0 $ 0
Wiltel Guarantee [Member]    
Additional disclosures:    
Guarantor Obligations, Maximum Exposure, Undiscounted 20  
Indemnification Agreement [Member] | Carrying Amount [Member]    
Additional disclosures:    
Guarantees $ 0  
[1] The carrying amount is presented net of counterparty offsetting arrangements and collateral (see Note 8 – Commodity Derivatives)